John,
>2. There is no default supplier. The user must select a supplier. An add validates for empty supplier ID (control source of comboB) and an edit of the item # clears the supplier ID, forcing a new supplier choice. Yes I could put it in the lost focus of combo A, but I prefer to keep code that affects a control in the control if possible. It makes it easier to find.
How about requery() the view and combo in its own refresh method. Then in the first combo, fresh the form in its lostfocus(). But keep in mind, it is possible to, for example, click a save button on a toolbar without the actual combo loosing focus. I use VFE so this is all done for me, but I think you need to hook into the lostfocus() of the form.
HTH